Conventionally, a process for industrially producing (meth)acrylic acid by gas-phase catalytic oxidation of a (meth)acrylic acid production raw material has been known. A (meth)acrylic acid-containing gas produced by gas-phase catalytic oxidation of the (meth)acrylic acid production raw material is, for example, collected by a liquid medium to be recovered as a crude (meth)acrylic acid solution, and then, the crude (meth)acrylic acid solution is purified by methods such as distillation, diffusion, extraction, crystallization, or the like.
Patent Literature 1 discloses a method for purifying a crude (meth)acrylic acid solution by crystallization. In the case where a crude (meth)acrylic acid solution is purified by crystallization, cooling is needed for crystallizing (meth)acrylic acid from a crude (meth)acrylic acid solution, and heating is needed for obtaining purified (meth)acrylic acid by melting crystallized (meth)acrylic acid. However, Patent Literature 1 does not specifically describe a method for cooling and heating in the crystallization.
Patent Literature 2 discloses that cooling water generated by an absorption refrigerator is used in a crystallizing step when a crude (meth)acrylic acid solution is purified by crystallization. However, Patent Literature 2 does not describe techniques for stable operation of the refrigerator in the crystallization and reduction of consumption energy of the refrigerator used as a heat source device.